Automatic reclosing circuit-breaker system



April 30, 1929. J, W, MCNAIRY 1,710,939

AUTOMATIC RECLOSING CIRCUIT BREAKER SYSTEM Original Filed Oct. 3, 1924 Fig. 1.

Inventor: Jacob W. McNcLirg, b9

His Attorneg Patented Apr. 30, 1929.

UNITED S ATES IPA-TENT OFFICE.-

JA COB W. MCNAIRY, 0F SCHENECTADY, NEW- YORK, ASSIGNOR TO GENERAL ELEC- v- TRIO COMPANY, A CORPORATION OF NEW YORK.-

AUTOMATIC RECIlZOISI NG C1RCUI'Ij-BREAKER sYsTEMQ Application 'fiia Qc tober a; i924, Serial My presentfinvention relates to automatic reclosing circuit 1 breaker systems and apparatus and particularly to such systems whereinan automatic circuit breaker is held inthe J closed. position by normally energized electrical 'mea'ns and is arranged to operate sequentially with other switching apparatus in controlling electric circuits, v i n The invention'has for its'object the provision in a system of the above character of a novelarrangement of control apparatus and circuits for increasing theholding force of the electrical means du ring the closure of the circuit breakerand until after the operation of the other switching apparatus.

In the co-pending joint patent application Serial No. 683,533, filed Dec. 31, 1923, by John F. Tritleandmyself, the'reis disclosed and broadly claimed a control systeinand'apparatus whereby the attractiveforce of the holding electromagnet -ofa 'circuit breaker which is Y electromagneticallyi' held the closed position may be increased duringlthe closure of. the breaker in order to prevent the accidental opening thereofdue to the jar'or shock necessarily accompanying the closing operation, illustrated 'in the above application, the increase in the attractive force of the holding electromagnet during closure of the breaker is effected by a manually operated push .but-

ton which is arranged to establish a shunt circuit around a resistance in circuit with the normally energized holding electromagnet and at the same time to effect the operation of the closing mechanism of the breaker.

' When such a circuit breaker'is arranged to operate sequentially with other automatic switching apparatus, as for example in'automatic recl'osing circuit breaker systems such as described and claimed in the Anderson Patent No. 1,546,879, issued July 21, 1925, and the McDonald Patent No. 1,534,724, issued A pril 21, 1925, both of which are assigned to the same assignee as my present invention, it is desirable that the over excitation of the holding electromagnet be continued automatically untilafter the operation of the other switching apparatus has been effected in order to prevent the accidental or premature opening of the breaker. Otherwise the breaker may be opened out of proper sequence, particularly when the breaker is subjected to a current surge near is supplied from the supply line 10 In the particular e'mbodiment' N5. 741,436. Renewed October a; 19 28.}

reliable arrangement of control apparatus and circuits whereby t-heholding electromagnetof'the breaker may beover excited until after the opei'ati onjof the other switching apparatus has been effected in "such automatic reclosin'g systems 'alth o'ugh" the 1 inven tion is not necessarily limited-thereto.

A better understanding of the invention may be had from the following description of the accompanying drawing in which Fig. 1, diagrammatically illustrates the invention embodied in an automa'tic'reclos'ing circuitbreaker system for controlling a feeder circuit and Fig. 2, is a circuit diagram of an automatic load limitingprotective systemifor a dynamo electric machine'likewise embodying the invention I a The novel features and combinations which I'believe to be characteristic'cf my inventiona're pointed outwith particularity in the appended claims: z Y j Referring .to Fig; 1 of the drawing, power n to the feeder line 11 which'is connected through an electrical translating device T, such as amo- .tor, transformer, or the like, to ground. 1 The power supply circuit extends through the overload circuit breaker 12 which is biased to the openposition in which it is shown and is elcctromagnctically held in the closed position by a normally energized holding electromagnet 13. In the preferred form shown, the circuit breaker 12 is of the high speed trip free type described and claimed in the Tritle Patent N0. '1,560,440,-issued November 3, 1925, and assigned to the same assignee as my present invention although other types of circuit breakers may be employedif desired. Cir: cuit breaker 12 as illustrated, is operated to the closed position by a closing electromagnet 14 and is provided with a bucking bar 15 which is arranged to effect the opening of the breaker automatically upon the occurrence of overload or short circuit conditions on the feeder line 11. The automatic reclosure of breaker 12 is accomplished upon the recurin circuit with the energizing winding of elecof the operation :follows: Y

troihagnet 13 and is arranged to be short circuited by means ointly controlled b y the breaker 12 and contactor16 in a manner which will be better understood from a description of nyinvention which is as Assuming that thesupply line is ener- "gi'ze'd'from a suitable source of supply such time delay relay as illustrated and thatthe breaker 12 has been operated to the open position in which it is shown in r'espo'nse'to an overload on the feeder line 11, a n energizing circuit for the 18is established from the supply line 10 through'the auxiliary contact 21 of feeling out cont-actor 16, the auxiliary contact 2210f circuit breaker 12,'through the operating winding of relay 18 and the lower contact 23 of discriminating relay 17 to round. After a time interval, time element rela 18 closes its contact 24 and opens contact 25, thereby establishing energizing circuits through the contact 24 for both the time element relay19 and the feeling out contactor 16, the'c'i rcu it of the latter extending through the auxiliary contact 26 of breaker 12 and the voltage reducing resistor 27. Contactor 16 at once closes and connects the feeder line 11 to the'supply line 10 through the current transformer 28 and the feeling out resistance 29 which is proportionedto maintain the resulting current flow within desirable limits. The time relay 19, however, requires a certain period for operation of its contact to the closed position after the feeder line 11 is connected to the supply line 10 through the feeling out resistor 29. This permits the selective operation'now to be described to occur.

It will be observed that the operating winding of discriminating relay 17 is connected to be energized from the current transformer 28 and thus is energized responsively to the rate of change of current in the feeling out circuit. If the rate of change of current exceeds a predetermined value, the relay 17 operates its circuit controlling contacts, 23 and 30 from the closed position to the open position wherein they are mechanically held by the latch 31. Upon the opening of contact 23, the energizing circuit of time element rcz to increase the energization of the holding electromagnet 13 durin the closure of breaker 12 and until ,aften the resulting 1 operation of the feeling out contactor 16 to jt-liefopen position, the resistor 20 is connected I contacts 23 and lay 18 is interrupted and the latter immediately returns to the position'in which it is shown, thereby opening the energizing circuit of both time element relay 19 and feeling out contactor 16, each of which also returns to the position shown. At the same time the reclosure of contact 25 of time element relay 18 establishes an energizing circuit for the resetting electromagnet of the discriminating relay 17 extending from supply line 10 through the contacts 21 and 22, the resistance 33, contacts 25, and the winding of electromagnet 32 to ground. The resulting energization of electromagnet 32 releases latch 31 thereby permitting the contacts of discriminating relay 17 to return to the position in which they are shown. l V

The reclosure of contact 23 again energizes the time element relay 18 and the latter after the time interval required for closure of-contact 24 effects the energization of both feeling out contactor 16 and time. element relay 19 in the manner previously described. Thereupon the feeling out contactor 16 reconnects the feeder line 11 to the supply line 10 through the current transformer 28 and the feeling out resistance 29 as previously described. v 7

If the overload or short circuit on the feeder line 11 had been removed so that the resulting rate of change of current through the transformer 28 is below the value at which the 'idiscriminating relay 17 is adjusted to pick up its 30, the relay 18 will be maintained closed and consequently the time element relay 19 will be -mainta1ned energized through the contact 24 of relay 18 for a sufficient time interval for the time element relay 19 to operate its contact to the closed position. Upon closure of the contact of time element relay 19 the operating winding of reclosing relay 34 is connected in shunt with the resistance 20 through a circuit extending from the grounded end of the resistance 20 through the auxiliary contact 35 of feeling outcontactor 16, the contact of time element relay 19, and the winding of relay 34 to the other end of the resistance 20. This energizes. the reclosing relay 3 1 responsively to the voltage drop across the resistance 20 and the additional current flowing through the winding of relay 34; increases the energization of the holding electromagnet 13 of circuit breaker 12. The resistance 20 is in a series circuit with the operating winding of the normally energized holding electromagnet 13 extending from the supply line 10, through the winding of the holding electromagnet 13 and thence through the resistance 20 to ground. The resistance 20 thus serves to limit the energizing current of the holding electromagnet which flows in the series circuit. However, when the operating winding of relay 34 is connected in multiple with the resistance 20, this provides a shunt path around the resistance 20 and permits more energizing curmagnetic armature 35 is held by the"l1ol ding 13 with however-the cii-"cuit electromagnet 'cont'rollin contacts-36' and 37 0f the breaker disengaged Due to the trip free feature of the Tritl'e type of'eircuit breaker, the contacts 15 36 and 37 are maintained disengaged until after thede-energization' of the closing elec- "tromagnet l t which is accomplished in the following-manner. I -During the operation of circuit breaker 12 to the intermediate position, the auxiliary contacts '22, 26 and 38, associatedtherewith are operated in thefollowing manner. Contact 22 is disengaged from the-left hand stationary contacts -co-operating therewith, thus 25 deenergizing the time element relay- 18. At

substantially the same time contact '26 is opened and contact 38 closed to connect the winding of-the-feeling out contactor 16 in shunt circuit with the feeling out resistor 29. Also contact 22 is bro ght into engagement with the right hand stationary" contacts thereby well as the operating winding of relay 34, the shunt circuit in each case extendingthrough the contact 35 on the feeling out c-ontactor 16. The short circuiting of resistor 20 causesthe holding electromagnet 13 to be further overexcited by reason of the full "cit-age of supply line 10 being impressed thereupon. The short circuiting of the winding of relay 34 causes this relay to open. Upon the opening of relay 34 the energizing circuit of closing electromagnet 14 is interrupted and the latter returns to the position in which it is shown thus permitting the circuit controllingcon- .tacts 36 and 37 to engage and complete the circuit through which feeder line 11 receives power from the supply line 10. During the closure of breaker 12, the operating winding of feeling out contactor 16 is connected in shunt with the feeling out resistance 20 through the auxiliary contact 38 which is-arranged to close slightly before or simultaneously with the opening of contacts 22 and 26-as previously described. Thus with the feeder line 11 connected to an ap preciable load, contactor 16 is maintained energized responsively to the voltage drop across resistance 29, while with no appre- G0 ciable load, the resistance 29 serves as a low resistance shunt for the'windingof eontactor l6 and thereby delays the opening of this contaetor by preventing the rapid decay of the flu): thereof. In this way the feeling out contactor 1G is maintained closed so as to inbreaker establishes a short 'ing of auxiliary 's1stance'2O again-lnserted in circuit with the -vent flashover of the generator 'surethat the holding elect romagnet 13 is maintained -overexcited by the short circuiting of resistance 20 until after the engagement of the'circuit breaker contacts 36 and 37. The elosingof the contacts of the circuit circuit around the feeling outresistanee 29. The short circuitiug of resistance 29 due to closure of the circuit breaker contacts also serves to short-circuit the operating winding offeeling out contactor 1.6. As soon as the decay of flux in the short'circuited winding of the feelingout contactor 16-per1nits, this contactor returns -to the open position'and interrupts the short circuit around the resistance 20 by the opencontact '35. With the rewinding of -ho'lding eleetromagnet- '13, V the energi-zation' thereof is reduced .to the: normal value and circuit tion to afford thenormal-overload protection for feeder line -1:1 for which the breaker :is

cali brated.-'

It will be evident thatzby over' excitingthe holding electromagnet 13 in the manner just described, the accidental or premature opening of the breaker due to jars shocksior' current surges near the tripping value occurring during th'e'closing operation'thereof and until after the "feeling: out contac'tor has opened, is effectively prevented. entirely short circuiting the resistance 20 as Referring now' to F 2 which illustrates the invention embodied in a an automatic 'load limiting protective system for a dynamo electric 'machine such as the-direct currentgenerator 40, it will be observed that-a high speed, trip free circuit breaker12of-the Tritle type previously described is connected in the negative side of a direct current generator40 and is arranged to operatesequcntiallywiththe line contactor 41 in protecting the generator from overload or short circuit current. The'load limiting resistors 42 and 43 are connected in the circuit through-which generator 40 supplies power to the supply'line 10 and the re 'sistor-42 is of suitable ohmic value to nraintain the'current supplied'by generator 40 Within desirable limits upon a moderate overload on supply line 10 while the resistor 43 is of such ohmic value as to effectively pro 40 on a heavy overload or even under short circuit conditions. A short circuit around the load limiting resistor 42 is controlled by the electromagnetic switch 44 which in turn is controlled under moderate overload conditions by the overload relay 45 and the resistor 43 is arranged to be short circuited when the circuitbreaker 12 is closed and is inserted in the generator circuit upon the opening of the breaker.

Line contactor 41 is electrically'interlocked with the circuit breaker 12 so that the formeropen position after the 12 and is operated to the is operated to the openin of breaker breaker 1 2.againis in' condiage induced by the load on supply line 10 rentlimiting resistor 43 in circuit to prevent a fiashover on the commutator of the generator 40 operating closed position after the closure of breaker 12.

In order to prevent the accidental opening of circuit breaker 12 during the closing operation thereof as well as the premature opening thereof upon 'the occurrence of a temporary current surge when the line contactor 41 is closed, the holding electromagnet 13 of breaker 12 is arran ed to be over-excited during'the closure of breaker 12 and until contactor-41 has been operated to the closed position. -The manner in which this is accomplished will be more clearly understood from a-description of the operation of the automatic 'loa d limiting-system embodying my invention which is as follows:

Assume that the high speed circuit breaker 12 has opened responsively to a heavy overand inserted the curand that consequently the switch 44 has opened and contactor 41 has been operated to the open position to disconnect the generator 40 from the supply line 10. VViththe contactor- 41 and the switch 44, in their-respective open positions as shown, the winding of 'reclosing relay 34 is connected in shunt with the voltage reducing resistance 2O. through a :circuit extending from the grounded end of resistance through the auxiliary contact 46 of line switch 41, the auxiliary contact 47 of switch 44, and the winding of relay 34 to the other end of resistance 20. This both energizes the reclosing relay 34 and over-excites the holding electromagnet'13 of breaker 12. Upon responseof relay 34, the closing electromagnet 14 of breaker 12 is connected across the armature of generator 40 and the current limiting resistance 43 in series circuit and is thereby energized to operate the breaker and carry the movable magnetic armature 35 into engagement with the holding electromagnet 13. The resulting operation of breaker 12 closes the auxiliary contacts 48 and 49 and the former establishes a short circuit around the operating winding of the closing relay 34 as well as around the resistance 20 thus (lo-energizing the relay and further over-exciting the holding electromagnet 13. Contact 49 connects the operating winding of line contactor 41 to the ungrounded termi nal of the closing electromagnet 14 but until the contacts of the reclosing relay 34 are opened, the contactor 41 is not energized since the operating winding thereof is connected between points of equal potential. Upon the opening of the contacts of reclosing relay 34 and the consequent de-energization of the closing electromagnet 14, the energization ot the operating winding of line contactor 41 is further delayed due to the voltdecaying flux in the closing electromagnet 14. Thus the energization of line switch 41 is delayed until after the engagement of the circuit controlling contacts 36 and 37 of breaker 12. 'Ihereupon the current flowing through the operating winding of line contactor 41 and the operating winding of closing electromagnet 14 in series circuit is suliicient to operate the former to close its contact but is insufiicient-tooperatively energize the closing electromagnet 14 since the winding of the latter is of relatively low resistance.

\Vhenthe line switch 41 finally responds to connect the generator with the current limiting resistance 42 in circuit therewith to the supply lines 10, the auxiliary contact 46 is opened thereby interrupting the shunt cir-; cuit around the resistance 20. This reduces the energization of holding electromagnet .13 to the normal value and the breaker 12 is again responsive to open upon theoverload current for which it is adjusted.- v .1

Upon the closure of line contactor 41,'a circuit is established from the supplyline .10 through the operating winding of resistance controlling switch 44, thecontact 50, the voltage reducing resistance '51, thecontacts of current relay 45, the auxiliary contact 49 of breaker 12, and the winding of closing electromagnet 14 to ground. Thus the switch 44 is placed under the control'of the currentrelay 45 and the load limiting r'csistor.42 is maintained in circuit with the generator 40 when the current suppliedby the latterto supply line 10 is'above'the predetermined value at which the current relay contacts are opened and is short-circuited when the gen-' erator current decreases below thepredetermined value atwhich the current relay-45 closes its contact and energizes the switch 44.

Should a heavy overload or short circuit then occur on the supply line 10 as was initially assumed, the circuit breaker 12 immediately operates to insert the current limiting resistor 43 in the generator circuit and at the same time to open the circuitcontrolled by auxiliary contact 49 through which both:linev contactor 41 and resistance controlling switch 44 are energized. The automatic reclosure of the breaker and line cont-actor 41 is effected in the manner previously described with the holding electromagnet 13 of the former over-excited until after closure of the latter.

In accordance with the patent statutes, I have described the principle of operation of my invention together with the apparatus which I now consider to represent the best embodiment thereof, but I would have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is 1. In an automatic reclosing circuit breaker system the combination of an automatic circuit breaker having normally energized electrical means for holding the breaker in the closed position, an electromagnetically operated switch controlled by said breaker and arranged to be operated to one position after the opening of. the breaker and to another positionafterthe closure of the breaker, and means jointly controlled by said breaker and said switch for increasing the holding force of said-first.ineansduring the closure of the breakera-nd until afterthe said switch is operatedto the said other-position.

:2: In an automatic reclosing circuit breaker systein,Ethecombination of an automatic circuitqbreakerphaving a normally energized electroniagnet for holding the breaker in the closed-.- position, a resistance in circuit with said electromagnet, an electroniagnetically zoperatedjswitch controlled by said breaker aiidnarranged-tobe operated one position after the opening of the breaker and to anotheinposition after the closure of the breaker, and connections-jointly controlled by said breaker-and said, switch for short circuiting said res'istanceduring the closure of the breaker and until the said switch is operated to the saidother position.

3. I-nfanautomatic. reclosing circuit breaker-systeni, the combination of an automatic ciruit breaker having eletroresponsive closing ineansand independent normally energized electrical means for holding the breaker in the closed position, .an electromagnetically operr-ated switch connected to be controlled by said breakei-and arranged-to be operated to one position after :the opening of the breaker and to another. positionafter .the closure of the breaker, and means jointly controlled by said --breaker and said switch for energizing the said closing means and simultaneously increasing the holding force of said holding means during the closure of the breaker and until after the electromagnetically operated switch is operated to said other position.

4. j Inan automatic reclosing circuit breaker system, thevcombination of an automatic circuitbreaker having a closing electroinagiiet and an independent normally energized electroniagnet for holding the breaker in the closed position, a resistor in circuit with said holding electromagnet, an electioniagnetically operated switch connected to be controlled by said breaker and arranged to be operated to one position after the opening of the breaker into another position after the closure of the breaker, and connections jointly controlled by said breaker and said switch for energizing the closing electromi-ignct and short circuiting said resistor during the closure of the breaker and until after the said switch is operated to said other position.

5. In an automatic reclosing circuit breaker system, the combination of an automatic circuit breaker having a closing electromagnet and a normally energized holding clec jointly controlled by said breakerandsziid switch for controlling said resistance to increase the energization of said holding elec-;, tromagnet simultaneo usly withthe de-energization of said closing electr0inagnet;.. Y

6. In an automatic reclosing circuit breaker system, the combination of an automaticcin j cuit breaker having a closing electromagnet and a normally energizedholding V magnet, a resistance in circuit witl saidholding electroinagnet, an electromagnetieswitch Y arranged to cooperate with said breaker in controlling a circuit, means associated .with

electro said breaker and arranged to control the energization of said switch to operate the same-to one position when the breaker is opened and to another position when the breaker is closed, an auxiliary switch mechanism associated with said breaker and with said switclrand con-.

nections jointly controlled thereby for short circuiting said resistance toincrease the encrgization of sa d holding electromagnet during the closure of the breaker and until the said switch is operated to said other position. i

7. In an automatic reclosing circuit breaker system, the combination with an automatic circuit breaker having a closingelectromagnet and a normally energized holding electromagnet, an electromagnetic switchcontrolled v by said breaker and arranged tobe operated to one position afterthe breaker. is opened and to another position after 7 the ,breaker is closed, connections whereby the saidvclosing clcctroniagi'iet is energized to close the breakor when the said switch'is in said one position, and means jointly controlled by said breaker and said switch for de-energizing said closing elcctroinagnct and increasing the energization of said holding electroiiiagnet during the closure of the breaker.

8. In an automatic reclosing circuit breakor system, the combination with an automatic circuitbreaker having a closing electromagnet and a normallycnergized holding electromagnct, a resistance in circuit with said holdin g cleclromagnet, an electromagnetic switch assoi-iated with said breaker and arranged to be operated to one position after the breaker is open a nd to another position after the breaker is closed, an electromagnetic relay for connecting the said closing electromagnet to a source of power, and connections jointly controlled by said breaker and said switch for energizing the winding of said relay in shunt 'ith said resistance upon the operation of said switch to said one position and for short circuiting the said relay and said resistance upon and-to another position upon closure of the breaker, and-connections jointly controlled by said breaker and said switch-for simultaneous- 1y energizing-said-closing electromagnet and increasing the energization of said holding electromagnet'wh'en the breaker is opened and said switch is in said one position and for deenergizing the said closing electromagnct and maintaining the said holding elcctromagnct over ene'rgized during the closure of the breaker and until after the said switch is 0perated to the said other position.

10.'-In "an automatic reclosing circuit breakersystem, the combination of an automatlc'circuit breaker having a closing electromagnet and a normally energized hblding eleet'romagn-et electromagnetic switch inC l1 anism for controlling said breaker and arrangedto beset into operation upon the opening of the breaker for energizing said closing electromagnetto'reclose"the breaker, and to beset into'operation'upon the closure of the breaker toreturmto its initial position and means jointlycontrolled by said breaker and said'electromagnetic switch mechanism tor increasing the holding force of said liold'ng electromagnet during the closure of the breaker and until after the said switch mechanism has returned to its initial position.

11. Ina'n automatic reclosing circuit breakor system, the combination of an automatic circuit breaker having a closing Gl(!('.tl'0l!llgl lot and a normally energized holding electromagnet, electromagnetic means set into opera tion upon the opening of the breaker for energizing said closing electron'iagnet rcspon' sively to the electrical condition of thc circuit controlled by said circuit breaker and comprising a resistor and an electromagnetic switch for connecting said resistor in shunt with the circuit controlling contacts of said circuit breaker when the same are in the open position and for interrupting the said shunt circuit upon the closure of the breaker, and means jointly controlled by said switch and said circuit breaker for increasing the holding force of said holding electromagnet during the closure of the breaker and until after the said switch has operated to interrupt the said shunt circuit.

12. In an automatic reclosing circuit breaker system, the combination of a circuit having a current limiting resistance connected therein,- an auton'latic circuit breaker for short-circuitingsaid resistance and having a closing electromagnet and a normally energized holding electromagnet, an electromagnetic switch controlled by said breaker and arranged to open said circuit upon the opening of said breaker and to close said circuit upon the closure of said breaker, and means jointly controlled by said breaker and said switch for increasing the holding force of said holding electromagnet during the closure of the breaker and until after the said switch has operated to close said circuit.

13 In an automatic reclosing circuit breakor system the combination of a circuit having a current limiting resistor connected therein, an automatic circuit breaker for controlling a short circuit around said resistance and having-a closing electromagnet and a normally energized holding clectromagnet, a resistance in circuit with said holding electromagnet,an electromagnetic switch cont-rolled by said breaker and arranged to be operated to open said circuit upon the opening of the breaker and to close said circuit upon the closure of the breaker, and connections jointly controlled by said switch and said breaker for simultaneously controlling said second re sistance to increase the energization of said holding clectromagnet and energizing said closing elcctromagnet when said breaker and said switch. are in their respective open posilions and for de-energizing said closing electri'n'i'iagnotand maintaining the said holding electromagnct oxcr-encrgized during the closure of the breaker and until after closure of said circuit.

In witness whereof. I have hereunto set my hand this 9nd day of October, 1924.

JACOB w. McNAIRY. 

